HTML website issues to fix

Hi! I have some issues on my website to fix.

First of all, it is a portfolio website with a home page on top and 3 sections ABOUT/WORK/CONTACT. 'Work' section has clickable elements which takes you to separate portfolio pages once clicked.

What needs to be fixed:

1. (the most important) Half of the screen needs to be static while the right side is scrolling. When the scrolling on the right side comes to an end, both sides switch to the new section. See the attached file. It is done but not very smooth at the moment. Once this is fixed, same will apply to 'about' section which has text on the right side instead of images but the principle is the same. ('Contact' need no fixation as it is not overloaded with text or image.)

2. The home page animation is not as I wanted so I would like to change it. I have a logo, text underneath the logo and a background. Not very complicated... I think all needs to be fixed is the position, styling and timing for the elements. That's about it.

3. There are some animation codes come with the old template files which animates the text & images from bottom to top and in theory, this was to be seen on portfolio pages but it does not work.

4. Portfolio pages back button is not working sometimes. Not sure if anything can be done to fix this issue. Code may need some clean up.

5. Portfolio elements ('work' section) has 'MORE' button on top of their images. The styling on the button will change & same button to be used as 'next' button to the bottom of every portfolio page which is linked to the next portfolio page.

The site is done on html. I can share the files on github.